Black room
by Tribbs
Summary: Starts straight after Lucifer possesses Castiel in episode 11x10. Lucifer claims he can beat Amara. But is he as dedicated to the cause as he claims? Cas has barely been holding it together since Rowena cast the attack dog spell, how will he cope with nothing but his own doubts and fears to keep him company? First ever fic. Reviews would be appreciated!
**Chapter One.**

Cold. Bone deep and wearying. Castiel shivered and tried to focus on his surroundings, but the black room was featureless. A faint light allowed him to see the bare black walls, ceiling and floor. The room was empty of everything but Castiel. No sounds except the pounding of his heart and his slow steady breaths.

It seemed as if Lucifer had pushed him deep down inside himself and left him alone in the dark. The silence was deafening. He could no longer hear his brothers and sisters. He was alone. It was terrifying.

Why hadn't he even bothered to let Castiel dream or relive a pleasant memory? It was what Cas had done for Jimmy Novak, the previous owner of this vessel, before his demise when they were both destroyed at a subatomic level a few years previously.

When Castiel had been resurrected in this vessel, it had been empty. Jimmy was now in Heaven.

He stood and paced out the space around him. It was only just bigger than the height of his vessel in each direction. _Too small!_

He felt the rising panic in his chest and began to breathe in short sharp gasps, heart pounding in his chest and the sound of blood rushing in his ears. He fell to his knees.

"What have I done?!" He moaned brokenly. His head in his hands.

Vague glimpses. Never a full picture of what was happening outside. Brief moments in time that bled through the veil that held Castiel back. Whenever Lucifer felt something strongly, the veil seemed to slip slightly, allowing Castiel to see through Lucifers eyes.

Sam and Dean, unaware of the agreement, leaving the cage, the long walk out of hell ahead. The Winchesters driving away. _I know Castiel, you love them, I won't hurt them. I let them go. See?_

Rowena, lying dead, head at an unnatural angle. Castiel actually felt Lucifers spike of mirth at the sight. _Stupid_ , _vain woman, she actually thought I cared. That she could have influence over me. The witch would put us all in danger for her own ends._

Cas had hated Rowena, but such an end was unworthy of anyone.

Crowley's terrified expression as he was dragged across the floor by his former subjects to be thrown at Lucifer's feet. _This dog bit the hand that fed it._

Again, Cas felt little sympathy for the demon, but this was not why he had agreed to be Lucifer's vessel. He began to protest, probing at the edges of the prison Lucifer had locked him in.

"Castiel. What are you doing?" Lucifers voice dripped honey, suddenly appearing a few feet away to the right of Cas as he pushed at the black walls. He had taken the appearance of his old vessel, Nick. "Do you need something?" Lucifer leaned against the wall, his arms folded and faced Castiel.

"You said you could beat her! What has making Crowley into a punching bag got to do with defeating Amara?" said Cas in irritation. His hands dropping to his sides he stepped towards Lucifer and coiled his fists in anger.

"Nothing, brother. But you have to admit, the little bastard has it coming, does he not?" He smirked.

"Besides, I need information. He has an army of demons just waiting for a leader. This is probably the best way to get it. We don't have to like it. Do we?"

He said in a reassuring tone. "Don't worry, brother. I have a plan." He looked around the blackness surrounding them "Castiel, I love what you've done with the place." he said dryly.

"This is _your_ doing!" snapped Castiel. "My vessel, Jimmy, was loved. He was never left like _this_!" gesturing with his hands to the dark room. Indignation radiating from him. Lucifer looked shocked. Castiel's shoulders sagged as the fight suddenly went out of him. Sadness at Jimmy's sacrifice taking over for a moment. He sighed and turned away from Lucifer. Unwilling for the archangel to see the emotion on his face.

"Are you saying I don't love you, brother? It was because I loved my Father and my brothers and sisters that I fell, remember?" Lucifer said sadly. "I do love you brother, I think... you being in this dark place is because you're not a human. You have no soul, and therefore no dreams. I'm... sorry brother. I truly am. I didn't know you would be left like this."

He looked genuinely upset for a moment. Before smiling tightly "It could be worse, you could be in Heaven!" He joked flatly.

Castiel whirled around to look at him with narrowed eyes, jaw clenched he muttered "It is not a joking matter Lucifer." Abruptly changing topic, he stood up a little straighter and looked Lucifer in the eye. "How will you defeat her?"

"Ah, brother. You are all business. I forgot about the giant stick up your butt. I would have thought you being human for a time and actually getting laid would have removed said stick. I was sadly mistaken." He sighed and continued "I have been away for so long, I need to find some items that I will need in order to beat her." Lucifer said vaguely "They are probably all over the world by now." Hands in his pockets he began to pace the floor around the edges of the room.

"What items?" Said Castiel, frowning. Ignoring the jibes.

"Items I need. From my Crypts." Lucifer said, even more vaguely. Still pacing.

"More tablets? Celestial weapons? Be clear, Lucifer!" said Cas sharply. Annoyed at Lucifers attempts to brush him off.

"Weapons, Castiel. Weapons. I had my brothers with me last time, this time I am alone. I will need any and every advantage I can get against her. With them, I can win." Lucifer said with irritation. "Stop worrying brother. I told you. I have a plan." He stopped and leaned back against the wall arms crossed in a relaxed pose, one foot crossed over the other.

Castiel frowned. He wanted to believe Lucifer. He wanted to believe that he had done the right thing in allowing Lucifer to possess him in order to beat Amara. Doubt ate way at him constantly, his previous mistakes still weighed on him heavily. He didn't care if he died in this fight. If it helped beat Amara, it would be worth it. That was the thing about being expendable and no less than he deserved after everything he had done. He only regretted not being able to say goodbye to the Winchesters. It hurt a lot to think of them. They would be angry with him. But it was for the greater good. Hopefully they would understand eventually.

"I understand." Castiel said quietly. "But we must move quickly, the longer we wait, the more damage she will cause." left unsaid was _Take her out before the Winchesters are killed trying to defeat her._

Castiel slid down the wall, sitting on his heels and dropped his head in his hands, running them through his hair. He pressed his palms over his eyes. The dark room pressing in on all sides. The silence unbearable. It was worse than when Metatron had stolen his grace. At least then he had been distracted from the silence by just trying to survive. The sting of full blooded human emotions undampened by grace had been almost too much to bear at first, and had never really gone away, but he had coped. He had survived. He had been lonely, but never truly alone like this. It was excruciating. He hoped that in his ignorance when he first took Jimmy as a vessel that he had never subjected him to something similar to this. He had not always been as attentive to the soul sharing the vessel as he should have. In the beginning, he had hardly thought of Jimmy _at all._

Lucifer watched Castiel with interest. He was a curious creature. Some of his mannerisms and colloquialisms were so... human. Yet he still maintained his angelic innocence and thus was easy to manipulate. _He's almost like a child._

"What will happen if you beat Amara?" Castiel said suddenly. Looking up at Lucifer directly across from him.  
"I don't know, brother. Lets get to one thing at a time shall we?" said Lucifer smoothly. He'd expected this question long before now. _Castiel must be suffering in this tiny dark room more than I thought. It should have been his first question._

"The Winchesters will not allow you to restart the apocalypse, Lucifer. _I_ won't let you." said Castiel vehemently. "If you try, we will stop you. We did before."

"And look how that turned out, hmmm?" said Lucifer snarkily "You all escaped unscathed! Oh wait, no. No, you didn't." Lucifer smiled at his own sarcasm. He said seriously "I have no plans as of yet Castiel. But you will be the first to know, if any of us survive this fight. Even if I beat her, it could still kill me. Lets cross that bridge when we come to it."

"Lucifer.." Castiel started.

Castiel suddenly slumped backwards as a wave of memories overtook him.

 _Thousands of angels lying dead, surrounding the new God as he made a speech. After millennia fighting side by side, he had started a civil war he could not hope to win without paying a terrible price. His brothers and sisters were butchered in the blink of an eye by his own hand. His desperate bid to save the humans had resulted in a massacre. It would not end there. He had many scores to settle, many wrongs to put right. He had only just begun. He would destroy anyone who opposed him. The power granted by the souls of purgatory would be enough to ensure victory and safety for the righteous..  
_  
"CASTIEL!" Lucifer was shaking Castiel by the shoulders. His booming voice cutting through the vivid flashback and pulling Castiel back into the present. He had gone almost catatonic.

Blue eyes wide in panic and fear, Castiel gasped as he struggled to get his breathing under control. Trying to focus on the present and not the crippling shame that threatened to overwhelm him.

He sat up, pushing Lucifer away from himself in disgust. "Don't touch me!" his voice a strangled sob. He pulled his knees up to his chest and buried his face in his arms.

"Castiel, I am trying to help you. We already share a vessel, you can't get closer than that, brother." He paused taking a deep breath "Was that a memory? You really did that?" said Lucifer a look of shock on his face.

"You almost destroyed heaven, proclaimed yourself a replacement for our father, but _I'm_ the monster under the bed, the bad guy condemned to a cage for eternity? I didn't kill a fraction of the angels you did. But our father saw fit to leave you unpunished?" His face a mask of incredulity.

He moved back from Castiel and ran his hand through his hair as he stood up and walked to the other side of the room his back to the angel. His shoulders sagging as he absorbed the impact of the memory.

"I... I thought I had no choice. I... could not afford to lose the war. Raphael would not listen. I.. tried to.. to.." stammered Castiel.

"The power was too much." he finished lamely. "I _was_ punished. I was resurrected as punishment. To face the consequences of what I had done. To atone for my sins." He hugged himself against the chill in the air. "Have you not seen my memories?"

Lucifer turned to face Castiel, his face impassive. "No, brother, not all of them. You must be unconsciously keeping them hidden from me." He paused "The angels, the ones from your faction, they still follow you?" He asked quietly.

Castiel closed his eyes and dropped his head back against the wall, still hugging his legs to his chest. "No." he said flatly. "Nor should they. They are rebuilding heaven without me, most of them despise me."

"That's something at least." snapped Lucifer crossing his arms and cupping his elbows. "You don't look so good." He said quietly, chin to his chest, looking down at Castiel.

"I've been better." said Castiel bitterly. "It... is too quiet. The other angels do not like me, but I miss their voices all the same. "

Lucifer walked slowly towards Castiel, hands held up in supplication as he approached. He stopped and crouched before Castiel. "Now brother, I will do my best to ease your suffering in here. I don't know how, yet. But I will try."

Castiel was suddenly alone again.

Lucifer lounged upon the throne of the former king of hell. Enjoying himself immensely.

Castiel would break faster than he'd hoped. Cutting him off from the voices of their brothers and sisters and isolating him in total darkness was genius.

But forcing him to relive his worst memories was a master stroke. He had lied about not seeing Castiels memories, he could see all of them laid bare. He was already halfway there, his delicious self loathing would destroy his own psyche.

Given enough time and pressure, his mind would crack and Castiel would _beg_ for Lucifer to hurt him, just to end the crushing loneliness and shame for a time. Revenge is a dish best served cold, after all.

His would be frigid.


End file.
